Tolong di jawab pake cara juga boleh

7-5m+(-8+15m)
= 7-5m-8+15m
= -5m+15m+7-8
= 10m-1

10-6m – (-8+15m)
= 10-6m+8-15m
= 10+8-6m-15m
= 18-21m

10m-1+10-6m
= 10m-6m-1+10
= 4m+9

18 – 21m

-1 + 10m

9 + 4m